1. Field of the Invention
The present invention relates to accessory modules designed for mounting on implantable fluid dispensing devices.
2. Background Art
A variety of fluid dispensing devices have attempted to more carefully regulate diseases or pain in patients by delivering drugs to particular sites within the body. For example, it is believed that insulin delivery by an implantable dispenser will regulate diabetes in a manner impossible through traditional injections.
These devices must be sealed to prevent migration of fluids between the patient's body and the interior of the device. The common technique has been to weld shut a metallic container, using technology similar to that in heart pacemakers. This method of sealing a case is effective, but is permanent and expensive to alter. Components within the case must be considered permanently encapsulated.
Particular applications of such fluid dispensing devices could be enhanced by having various accessories in combination with the permanent parts of the device, which reside within the case. For example, some drug therapies are safer if the drug is filtered for either particles or bacteria. Because each drug and therapy has specific characteristics, it is expensive and impractical to design a variety of such filters as part of the permanent apparatus sealed within the case.
Another example of an accessory for the module is a port for infusion of drugs on an acute basis, to supplement the chronic administration provided by the fluid dispensing device. Attempts have been made to add external ports to be used in conjunction with such devices. For example, see the port disclosed in U.S. Pat. No. 4,360,031 to White, issued Nov. 23, 1982. An external port is disclosed in U.S. Pat. No. 3,971,376 to Wichterle issued July 27, 1976.
A means is needed to accommodate such drug-specific and application-specific devices other than permanently mounting them within the sealed case. Great manufacturing expense can be saved if accessory devices can be added after the original manufacture. Better medical flexibility could be achieved if doctors could specify particular accessories to be added after manufacture.